The long-term objectives of this project are to: (a) Formulate an oral iron/ascorbic acid supplement specific to the needs of renal transplant recipients (RTxRs), (b) evaluate the efficacy of oral iron/ascorbic acid supplementation to meet the iron needs of this patient population as part of their routine post-transplant (post-Tx) care, and (c) establish a consulting service to work in collaboration with transplant/nephrology centers. Many RTxRs are at risk for iron-deficiency anemia. Most because they have absolute iron deficiency (AID) although some have relative iron deficiency (RID). An effective strategy to identify and treat post-transplant anemia (PTA) currently does not exist and its development necessitates insight into factors that affect iron absorption and utilization in RTxRs. We have recently developed a noninvasive method that permits evaluation of the efficacy of iron absorption/utilization. Our method is based on oral administration of a known amount of stable-isotope-labeled iron (58Fe), and the nonabsorbable marker DyCl3, followed by laboratory analysis of the ratio 58Fe -Excess/Dy in one or two stool samples and 58Fe -Excess in a blood sample obtained two weeks later. We propose to investigate factors that affect iron status of RTxRs and how to provide iron for their erythropoietic needs as part of their long-term care. During Phase-I, we will establish the feasibility of our overall strategy for meeting the iron needs of RTxRs by demonstrating that absorption/utilization of iron from low-dose ferrous ascorbate is sufficiently high throughout the post-Tx period in patients with AID to permit its use for this purpose. During Phase- IE, we will investigate parameters of iron supplementation-dose, frequency, most effective formulation of iron plus ascorbate - that are important for development of an effective strategy and in relation to issues such as immunosuppressive therapy.